Device for preventing noise in an oil-hydraulic elevator

ABSTRACT

A DEVICE FOR PREVENTING NOISE IN AN OIL-HYDRAULIC ELEVATOR HAVING AN OIL-HYDRAULIC CIRCUIT INCLUDING A ROTARY OIL FLOW CONTROL VALVE COMPRISING A ROTARY SPOOL IN THE SHAPE OF A CYLINDER ROTATABLY RECEIVED IN A SLEEVE, SAID SPOOL AND SLEEVE EACH HAVING A PAIR OF OPPOSITELY ARRANGED OPENINGS ADAPTED TO DEFINE A PAIR OF OPPOSITELY ARRANGED VALVE PORTS WHEN SAID SPOOL IS POSITIONED AT A PROPER ANGULAR POSITION WITH RESPECT TO SAID SLEEVE, SAID VALVE PORTS ALLOWING TWO OIL JETS OPPOSING TO EACH OTHER, THE METHOD BEING CHARACTERIZED BY PREVENTING CAVITATION AT AN OUTLET REGION OF SAID VALVE PORTS DUE TO COLLISION OF SAID TWO JETS BY KEEPING THE OIL PRESSURE AT SAID REGION IN A RANGE OF 0.5-5 KG./ CM2. SUCH AN OIL PRESSURE IN SAID REGION IS KEPT BY PROVIDING A BULLET-SHAPED GUIDE MEMBER OR A BAFFLE PLATE AT SAID REGION OR THROTTLING AND EXHAUST PASSAGE IN THE DOWN STREAM OF SAID VALVE PORTS.

Sept. 20, 1971 KEN c u ETAL 3,606,243

DEVICE FOR PREVENTING NOISE IN AN OIL-HYDRAULIC ELEVATOR Filedsepb. 12, 1969 3 Sheets-Sheet 1 OVER ALL FREQUENCY (HZ) INVENTORS KEN KA /Ry, Ila/m0 #aJlMwn,

ATTORNEY KEN ICHIRYU ETAL 3,606,243

Sept. 20, 1971 DEVICE FOR PREVENTING NOISE IN AN OIL-HYDRAULIC ELEVATOR Filed Sept. 12. 1969 5 Sheets-Sheet 2 INVENTORZ) ATTORNEYS Sept. 20, 1971 KEN ICHIRYU EI'AL 3,606,243

DEVICE FOR PREVENTING NOISE IN AN OIL-HYDRAULIC ELEVATOR Filed Sept. 12, 1969 3 Sheets-Sheet 3 FIG. 5a a;

INVENTOI-S ATTORNEYS United States Patent "ice US. Cl. 251-118 7 Claims ABSTRACT OF THE DISCLOSURE A device for preventing noise in an oil-hydraulic elevator having an oil-hydraulic circuit including a rotary oil flow control valve comprising a rotary spool in the shape of a cylinder rotatably received in a sleeve, said spool and sleeve each having a pair of oppositely arranged openings adapted to define a pair of oppositely arranged valve ports when said spool is positioned at a proper angular position with respect to said sleeve, said valve ports allowing two oil jets opposing to each other, the method being characterized by preventing cavitation at an outlet region of said valve ports due to collision of said two jets by keeping the oil pressure at said region in a range of 0.5- kg./ cm. Such an oil pressure in said region is kept by providing a bullet-shaped guide member or a baflle plate at said region or throttling and exhaust passage in the down stream of said valve ports.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to a means for preventing noise in an oil-hydraulic elevator, and more particularly a means for preventing noise perceived in a cage of an oil-hydraulic elevator due to cavitation caused by the exhaust of oil through a rotary oil flow control valve provided in an exhausting line of an oil-hydraulic system of the elevator.

(2) Description of the prior art Conventionally it has been thought that the noise in oil-hydraulic elevators is mostly due to the noise of oil pumps. However, we found that such a noise cannot be suppressed beyond a certain level even if the noise of the oil pumps is reduced almost to zero, and as the results of various experiments, we found that the noise is mainly caused by a particular structure of a rotary oil flow control valve provided in an exhausting line of an oil-hydraulic system of such an elevator. The rotary oil flow control valve used in such a system has a pair of oppositely arranged openings, and the oil flows ejected through these two openings collide with each other, thus generating cavitation which excites pipe lines, cylinders and/ or plungers to cause their vibrations.

SUMMARY OF THE INVENTION This invention depends upon the understanding of the above-mentioned phenomenon and has a first object to prevent the generation of the cavitation at an outlet region of a rotary flow control valve thereby to reduce the noise perceived in a cage of an oil-hydraulic elevator.

A second object is to obtain means effective for preventing the generation of the cavitation in a rotary oil flow control valve.

The above-mentioned first object is accomplished, according to this invention, by keeping and oil pressure in a range of 0.5-5.0 kg./cm. more preferably 1-3 kg./ cm. at an outlet region of a rotary oil flow control valve.

The second object is accomplished, according to this 3,606,243 Patented Sept. 20,

invention, by providing a bullet-shaped guide member or a baflle plate at said outlet region of a rotary oil flow control valve or by providing a contracted portion or throttling means at an exhausting passage connected to said outlet region.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawing,

FIG. 1 is a diagram showing an oil-hydraulic system of an elevator with which this invention is concerned;

FIG. 2 is an axial section of an essential part of a conventional rotary oil flow control valve used in the system shown in FIG. 1;

FIGS. 3 and 4 are somewhat reduced cross sections taken along line A--A in FIG. 2, wherein FIG. 3 shows a fully opened condition and FIG. 4 shows a fully closed condition;

FIGS. 5a, 5 b, 5c and 5d show several embodiments of means for preventing cavitation at an oil outlet region of a rotary oil flow control valve; and 1 FIG. 6 is a graph showing a comparison of the noises in a cage of an oil-hydralulic elevator with and without incorporating this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS ments of the plunger. Oil for operating the plunger is fed by a pump 5 driven by a motor 4 from an oil reservoir 6 via a strainer 7 and suction and delivery pipe lines 8 and- 9. From the delivery pipe 9 is branched a relief pipe line .10 which is returned to the reservoir 6 via an oil flow control valve 11 and an exhausting pipe line 12. The oil flow control valve 11 is adapted to be driven by a motor 13 and when it is fully opened, the oil delivered by the pump 5 is all returned to the reservoir 6. Now, if a push button (not shown) in the cage for a determined position is pushed, a control means (not shown) is operated and the motor 13 is energized to drive the valve 11 in the direction of closing its port, whereby the oil pressure in the pipe line 10 is increased. This increased pressure overcomes the pressure residing in a pipe line 14 and opens a check valve 15 to flow into the pipe line 14 and further to the cylinder 3. As the port area of the control valve 11 is more decreased, the flow of oil entering into the pipe line 14 is increased, whereby the movement of the cage 1 is accelerated. When the control valve 11 is fully closed, the cage reaches its highest velocity, and the motor 13 is stopped at this time. When the cage 1 has approached the determined position, a limit switch (not shown) provided in a passage of the cage 1 is actuated, whereby said control means is operated and the motor 13 is reversedly energized to drive the control valve 11 in the direction of opening its port. As the port area of the control valve 11 is increased, the flow of oil entering itno the cylinder 3 is decreased, whereby the cage is decelerated. The control valve 11 is then fully opened at such time when the cage 1 is just stopped at the predetermined position, wherein the oil in the pipe line 14 and the cylinder 3 is kept suspended by the check valve 15 being closed, and the oil pumped by the pump 5 is all exhausted through the pipe line 10.

When the cage 1 is to be moved downward from this position to a second determined position, a push button (not shown) in the cage for the second determined position is pushed, whereby an electromagnetic valve 17 in a branch pipe line 16 is opened to expose the underside of a check valve 19 holding the oil in the pipe line 14 to the oil pressure residing in the pipe line 14 thereby to open the check valve 19. At the same time a motor 21 of an oil flow control valve 22 provided in an exhausting pipe line 20 of the check valve 19 is energized to drive the control valve 22 in the direction of opening its port. Accordingly, the oil in the cylinder 3 is exhausted through the pipe line 14, check valve 19, pipe line 20, control valve 22 and drain pipe line 23 to the oil reservoir 6 thereby to let down the cage 1. When the control valve 22 has fully opened, the falling velocity of the cage 1 reaches the highest, and the motor 21 is stopped at this time. When the cage has approached the second determined position, a limit switch (not shown) provided in the passage of the cage is actuated, whereby the motor 21 of the control valve 22 is reversedly energized to drive the control valve 22 in the direction of closing its port. Thus, the downward movement of the cage is decelerated until the cage is finally stopped at the desired position when the control valve 22 is fully closed. At this time the electromagnetic valve 17 is returned to its starting position, and the oil which has been exerting a back pressure to the check valve 19 is exhausted through a pipe line 24 to the reservoir 6.

FIGS. 2, 3 and 4 show the oil flow control valve 11 in detail. As shown in these figures the control valve 11 comprises a rotary spool 31 in the shape of a cylinder closed at one end and having a pair of oppositely arranged openings 30 and a sleeve 33 firmly mounted in a valve body 32 and rotatably carrying the spool therein. The sleeve 33 has a pair of oppositely arranged openings 32 which are adapted to meet with the openings 30 of the spool when the spool is at a proper angular position. The spool 31 has a sprocket wheel 35 which is driven by the motor 13 via an endless chain 36. Reference numeral 34 shows a bearing. Thus, when the elevator cage 1 is to be elevated, the spool '31 is rotated from the position as shown in FIG. 3 where the openings 30 and 32 are superposed toward the position as shown in FIG. 4 where the openings 30 are shifted apart from the openings 32. When the cage has approached a position at which it is to be stopped, the spool 31 is returned from the position shown in FIG. 4 to the position shown in FIG. 3 by being rotated in a reversed direction. By rotating the spool in a reversed direction when it is to be returned to the starting position, the acceleration and deceleration of the cage at the starting and stopping regions are controlled at a same valve.

The oil flow control valve 22 is the stame as the control valve 11, except that the control valve 22 is normally closed and temporarily opened when the cage is moved downward, while the control valve 11 is normally opened and temporarily closed when the cage is moved upward.

In the conventional oil flow control valves 11 and 22, when the oil is passed from the pipe line 10 to the pipe line 12 or from the pipe line 20 to the pipe line 23, the oil is ejected from the oppositely arranged openings 30 so that two jets of oil collide with each other. Such a collision causes a revolutional flow which generates cavitation which causes fluctuation of pressure. The fluctuation of pressure excites the pipe lines and/ or cylinders to cause vibrations thereof, which are transmitted to the cage as a noise.

To suppress such a noise, this invention provides an improved rotary oil flow control valve in which the generation of the cavitation is efiectively avoided. For this purpose, in an embodiment shown in FIG. a, a bullet-shaped guide member 40 is provided in the spool 31 in a manner that the back pressure at an outlet region of the openings 30 is kept in a range of 0.5-5.0 kg./cm. If the back pressure is lower than 0.5 kg./cm. it cannot effectively suppress the generation of cavitation, While it the back pressure becomes more than 5 kg./cm. it influences the outlet velocity of oil and causes unstable movement of the cage. An optimum back pressure is in a range of 1-3 kg./cm.

In another embodiment shown in FIG. 5 b, the required back pressure is produced by providing a contracted portion 41 in the exhausting pipe line 12 (or 23). This embodiment shows a substantially same effectiveness as that shown in FIG. 5a.

To moderate a high sensitivity to changes of viscosity of oil of the embodiment shown in FIG. 5b, a third embodiment shown in FIG. 50 employs a cock, stop valve or other throttling means 42 for common usage. The throttling means may be used in singularity or in plurality in a proper combination. When the cock, stop valve or other throttling means has a relatively smooth flow passage and the flow resistance thereof is not too high, almost no cavitation is generated. In other cases, it is preferable that the back pressure is somewhat increased.

FIG. 5d shows still another embodiment wherein a bafile plate 43 is provided in the spool 31. In this embodiment there occurs a little cavitation at the outlet region of the openings 30, but since it is very weak, it causes almost no such noise as is transmitted so far to the cage. An experiment with this structure showed that the noise measured in a cage was lowered as much as about 6 phons.

In the embodiments shown in FIGS. 5b and 5c, cavitation is suppressed mainly by the effect of back pressure, while in the embodiments shown in FIGS. 5a and 5d, cavitation is suppressed by the effect of back pressure as well as by preventing vortex flow and thereby avoiding negative pressure caused at the center of vortex. Therefore, the embodiments shown in FIGS. 5a and 5d are effective for cases where strong cavitation is anticipated.

FIG. 6 shows a comparison of the noises in a cage of an oil-hydraulic elevator with and without incorporating this invention, wherein the abscissa represents frequency of noise and the ordinate represents intensity of noise. A solid line in the graph shows a noise spectrum measured in a cage of a conventional oil-hydraulic elevator when it is descending, and a broken line shows the same spectrum in a case of incorporating this invention in the form of the embodiment of FIG. 5a 50 that said back pressure becomes 2 kg./cm. As it is apparent from FIG. 6, the noise is reduced as much as about 8 phons. This result is also applied to the case when the cage is elevating, and can also be attained by the embodiments of FIGS. 5b, 5 c and 5d.

In the foregoing, this invention has been described when it is applied to an oil-hydraulic elevator having a bleeding-off circuit as shown in FIG. 1. However, it will be understood that this invention is equally applicable to any device which is provided with such a rotary fluid flow control valve as dealt with in this invention.

What is claimed is:

1. Device for eliminating noise in an oil-hydraulic circuit adapted to control the moving velocity of an elevator and including a rotary oil flow control valve comprising a rotary spool in the shape of a cylinder closed at one end and having a pair of oppositely arranged openings, and a sleeve mounted in a valve body and carrying said spool rotatably therein, said sleeve having a pair of oppositely arranged openings adapted to meet with said openings of said spool when said spool is positioned in a proper angular position, characterized in that said device is provided with means in the flow path from the openings for keeping the oil pressure at the open outlet region of said spool in a range of 0.5 kg./cm. to 5.0 kg./cm.

2. Device according to claim 1, wherein said means keeps the oil pressure in a range of 1.0 kg./crn. to 3.0 kg./cm.

3. Device according to claim 1, wherein said means includes a bullet-shaped guide member within said spool so as to keep the oil pressure at the open outlet region of said spool in a range of 0.5 kg./cn1. to 5.0 kg./cm.

4. Device according to claim 1, wherein said means includes a bafiie plate within said spool so as to keep the oil pressure at the open outlet region of said spool in a range of 0.5 kg/cm. to 5.0 kg./c1n. and to decrease the extent of cavitation therein.

5. Device according to claim 1, wherein said means further decreases the extent of cavitation in said spool.

6. Device according to claim 1, wherein said means 10 is provided within an exhausting pipe line adapted to direct the oil exhausted from said spool so as to keep oil pressure at the open outlet region of said spool in a range of 0.5 kgJcrn. to 5.0 kg./cm.

7. Device according to claim 1, wherein said means includes throttling means at an exhausting pipe line connected to the outlet region of said valve.

References Cited UNITED STATES PATENTS 1/1922 Beatson 137-625.32X

7/1936 Chadborn 137-62524 2/1960 Hempel 251-127X 8/1961 Becker 137-14 10/1969 Ciapetta et a1. 181-36X HENRY T. KLINKSIEK, Primary Examiner US. Cl. X.R. 

